Gun firing means



GUN FIRING MEANS Filed Aug. 16, 1945 AMP F CAT LI TAT QN SELEC ON CYCLE Enventor: 7 101m IP IV. M4971,

AM LIE IE TORAGE ACTUAT HG Pow R (Ittorneg.

rmma Mar. s, 1945 V Application August 10, 194:, Serial No. mass 1: Claims. cci. lei-4.5)

My invention relates in general to a method and means for controlling or producing an action at an inaccessible point below the surface of the earth and relates in particular to the firing of an explosive charge in a perforating gun positioned within-a casing in a well.

To provide openings in a casing in a well, through which oil may pass from the oil bearing formation into the interior space of the casing, perforating guns are now employed wherein the expansive force of an explosive charge is employed to propel a projectile through the casing wall, leaving an opening therein through which fluid may fiow from the formation into the casing. Perforating guns of this character are well, making it necessary to pull the gun so as to replace the faulty cable with another.

It is an object oi my present invention to provide a device and a simple'method for firing an explosive charge in a perforating gun which has been lowered into a well, which avoids the use of cable equipped with electrical conductors and avoids-the use of go-devils, thereby eliminating the disadvantages involved in the use of the old method and means referred to in the preceding paragraph. Where my new invention is emplayed, the service of perforating a casing in a well requires only transportation of relatively light equipment to the site of operations.

now fired by two difierent methods. One of these methods is to connect the perforating gun to an electric cable, that is to say, a cable having an insulated conductor extending therein, this conductor being connected to electrical firing means in the gun, and when the gun is suspended at the desired level time well, a current is transmitted through the conductor to actuate the firing means. The second method is to provide the perforating gun with a firing mechanism having a movable external part by which it may be actuated. The perforator gun, so equipped, is lowered into the well by means of a standard wire line or cable and a weighty object, called "godevil," is then slidably connected to the cable and allowed to descend within the well so that it engages the movable part of the firing device, and by moving the same, actuates the firing device. Reasonably satisfactory results have been obtained in the use of this method, wherein a firing member is placed around the cable and allowed It is an object of the invention to provide a method of firing a perforating gun in a well, wherein a gun is equipped with electro-responsive firing means, the lowering of the gun and the firing means into the well by use of ordinary wire line, cable, pipe or sucker rod, and transmit: ting electrification to the electro-responsive means by use of a simple device situated at the to descend so that it will strike an exposed part equipped cable is employed, has as disadvantages.

the necessity of transporting the specially prepared cable to each job, the handling of this cable at the job, upkeep and replacement of cable ow ing to the failure of insulation, and rupture of electrical conductors in the cable, the delay and labor encountered as the result of failure of insulation or electrical conductors in a cable while the gun is being lowered by the cable into the top of the well.

A further object of the. invention is toprovide a firing device adapted to be connected to a gun which is lowered into a well by use of ordinary wire line or cable, this firing means having a mechanismwhich is responsive to a characteristic electrical signal which is transmitted from the surface of the ground.

It is also an object of the invention to provide a method and apparatus wherein the electropotential signal is transmitted to the upper end of the casing which projects down into the well and in which the perforating gun is to be operated, and wherein the signal is picked up by the electr c-responsive control located in proximity to the gun through use of means wherein the signal is picked up by measuring the electro-potential drop along a portion of the casing or earth.

Further objects and advantages of the invention will be brought out in the following part of the specification.

Referring to the drawing which is for illustrative purposes only,

Fig. 1 is a schematic view showing a preferred form of my invention in the well.

Fig. 2 is a diagram of the electrical equipment ground so as to admit fluids from the exterior of the casing to its interior. I have showna perforatin: gun I: which may be of any known electrically operated type. For example, this gun [2 may be of any. of the types disclosed in one or more of the following U. S. patents: No. 1,582,184, No. 2,022,976, and No. 2,037,955, wherein electric current. ignites a fuse or primer associated with each of one or more charges of powder, and Patent No. 2,029,490, wherein powder charges are selectively fired in series relation instead of simultaneously.

The gun I2 is connected to 'a firing device or control [3, preferably by means of a comparatively short electrical cable 14a. The gun l2 and the device l3 are lowered into the well by means of an ordinary cable or wire line l4 so as to bring the gun I2 into the portion of the casing selected for perforating. The device l3 includes a water tight shell with an upwardly projecting cable attachment 16 which has around its lower portion an annular insulator H to support casing conwith the inner surface of the casing, resulting from the fact that the casing in a well which has been drilled to a considerable depth is not straight and that the cable will rub thereagainst at one or more bends in the casing. 'I have, however, for

purpose of illustration, shown such additional contact means as bow spring 20 clamped on the cable I4 so as to be electrically connected thereto, these bow springs sliding along and making contact with the interior of the casing Ill. The cages l8 and 20 are not necessary in all practices of the invention. For example, when there is salt water or mud in the well, contact with the casing or earth need not be made.

The device l3 has means which acts in response to impulses transmitted through the wall of the well to control or produce a useful act which, in the preferred embodiment of the invention, consists in the control or actuation of perforating means Within the casing.

The device l3, as shown in Fig. 2, includes a conductor 2| which connects the cage l8 with a condenser 22 which is connected to the grid 23 of readily interpreted or read by those acquainted with this art.

In the device shown in Fig. 2, the tubes 25, 25a, and 25b have a gain of fiftyv per stage or an overall gain of 2500 in the first two tubes, so that a very small 'eflective voltage will give practically square wave output from the tube 25b, which feeds into the voltage divider 21, and, since, the tube 25b is used to the limit of its voltage capacity, no greater voltage canbe drawn from the power supply provided by the ampliflcation section for the following parts of the equipment. Accordingly, this voltage divider 21, forming a part of the voltage limitation section of the device, has the effect of limiting the maximum voltage that can pass to the grid 28 of the tube 23. The voltage divider also furnishes a high impedance load to feed the' output of the cycle selection section of the de- .vice, which employs tubes 29 and 30 and in conjunction with the resistance and condenser network 3| form a selective circuit which determines the cycle or timing of the potential or electrical impulses which may pass through the conductors 32 and 33 to the grid and filament of the tube 34, forming a part of the power amplification section of the device.

The power amplification section transformer 35 having a secondary winding 35 which, through a thermionic rectifier 31 of the rectification section of the device, feeds a storage condenser 38 which forms the principal element of the storage section of the device. The final or actuating section of the device l3 includes an electrical valve shown as a grid glow tube, gastriode or diode, 39, connected in series with. the con denser 38 and with a means 40 which is responsive to a flow of current to produce an act or effect desired at an inaccessible point below the surface of the earth. The means 40 is shown as a high 40 resistance filament which heats or glows in rethe first tube 25 of the amplification section of the device. The filament 24 of this tube 25 is grounded through a conductor 26 with the cable I4 which is arranged to make electrical connection with the wall of the well, preferably the casing l0, at a point spaced from the cage l8. As hereinbefore explained, this contact of the cable 14 with the casing. l0 may-be through engagement of the cable l4 with the casing l0 at a bend therein, or by use of the bow springs 20 mounted upon and electrically connected to the cable M. In

the connection of the members l8 and 20 to the apparatus, transformer or impedance coupling may be employed, but I have preferred to use the resistance capacitance coupling shown in the upper part of Fig. 2. In the amplification section of the device I have shown three stages of common resistance capacitance coupled voltage amplifiers sponse to a flow of electric current therethrough so as to ignite a powder charge 4! in a powder chamber 42 of the gun l2, Fig. 1. This powder chamber 42 is disposed at the inner end of a gun barrel 43, and the effect of the burning of the powder charge 4| is to impel a projectile 44 outward at high velocity so that it will perforate the casing III. A high resistance conductant 45 is bridged across the storage condenser 38 to serve as a bleeder to bleed oil random pulses that might get through'the cycle selection section of the device, thereby providing a safety element. In the age of the condenser 38 reaches the break-down value of the valve tube 39, negative electrons will flow across from the cathode to the plate of the tube 39 and then through ,the electrically responsive means 40. Therefore, in order to actuate the means 40, it is necessary that the actuating imemploying three tubes which may be any of the 7 types known to the art of electronics. I have, however, shown tubes 25, 25a and 25b as being of the pentode type having A and B battery connection and associated condensers and resistances, etc., as' indicated in the diagram which may be pulses shall be fed to the condenser 38 for a period of time which is characteristic of the electrical values of the various parts of the device l3. If stray impulses pass through to the condenser 38, or the feeding of selected impulses to the condenser 38 is continued prior to the actuation of the valve tube 33, the bleeder 45 will bleed the conincludes a V dicated by lines 54, 55, 56 and 51.

connected to the top of the casing. These. im-

pulses may be unidirectional. alternating, or su-- perimposed. In Fig. l I show a commutator 4| drivable at constant speed by a motor 41. This commutator has segments and 49 connected to opposite poles of a direct current power source such as a battery 50. The segments 48 and ll are engaged by brushes II and 52 which are respectively connected to the casing III and to a. ground connection 53. The rotation of the commutator 46 results in the feeding of positive and negative electron impulses to the casing III, which flow down the casing and into the formation, such impulses passing to the ground connection B through divided paths in the formation as in- There is a potential drop along the casing, and therefore these electronic impulses produce a potential difference between the contact means l8 and 2., or a potential difierenc between input conductors 2| and 28 of the device l3. These impulses may be very small, but the amplification section of the device [3 under the control of the input impulsesv produces at the output of the tube 25b impulses of a magnitude to ultimately accomplish actuation of the electro-responsive means 40. For example, when the device I3 is at a depth of four or five thousand feet within the well, the impulses picked up by the input conductors 2| and "will the invention, the impulse producing means is value of the sub-surface structure varies'with' depth and also with the structural characteristics of the formations penetrated. My invention comprehends the use of impulse frequencies of per second and below. For depth greater than four thousand feet, I have employed a frequency .of seven impulses or cycles per second. The equipment, when adjusted for operation at such low frequencies, will, of course, operate satisfactorily at any depth within the well, although higher frequencies may be employed in the shallower wells, and under favorable earth conditions.

I claim as my invention:

l. A method of producing a desired action in an ele ctro-responsive device in a cavity below the surface of the earth, comprising: transmitting along the wall structure of the cavity impulses below the impulse suppression value of the subsurface structure between the position at which the impulses are originated and the position at which they are picked up; picking up these impulses at a position remote from the position at which they are originated and employing the picked up impulses to produce impulses of greater and operative magnitude; and directing these electrical impulses to an electro-responsive means for producing said desired action.

2. A method of producing a desired action in a cavity below the surface of the earth, comprising; transmitting through the earth electro-potential impulses in such a manner that they may be picked up along the wall of the cavity; picking be weak as compared to the impulses which are picked up when the device is positioned only one or two thousand feet below the surface of the ground, but when the device is operated within the range for which it is designed, the impulses transmitted through the limitation section to the A further feature of my invention is the use of a frequency of impulses-below the damping or impulse absorbing capacity of the earth ma- I terials which I have found to be effective against the passage of high frequency potential impulses down the wall of the well or downthe casing to any great depth. In the invention disclosed I produce, transmit, and pick up potential impulses having a frequency below a value which I term the impulse suppression value of the sub-surface structure, which includes both the well casing and the formation. This sub-surface structure appears to have an effect, such as a condenser or capacitance effect, whereby impulses are absorbed or suppressed, which suppression may be the moving out of the potential impulses to such an extent that the potential or current flow is substantially constant. This impulse suppression up these impulses at a position remote from the position at which theyare originated and employing the picked up impulses to produce impulses of a greater and operative magnitude; accumulating these electrical impulses so as to build up an electro-potential charge; and directing the electro-potential charge to an 'electro-responslve means for producing said desired action.

' 3. A method of producing a desired action in a cavity below the surface of the earth, comprising: transmitting along the wall structure of the cavity impulses of a frequency below the impulse suppression value of the subsurface structure between the position at which the impulses are originated and the position at which they are picked up; picking up these impulses at a position remote from the position at which they are originated and employing the picked up impulses to produce impulses of greater and operative magnitude; accumulating these electrical impulses so as to build up an electro-potential charge; and directing the electro-potential charge to an electro-responsive means for producing said desired action.

4. A method of producing a desired action in a well below the surface of the earth, comprising: transmitting along the wall structure of the well electro-potential impulses of predetermined character; picking up these impulses at a position remote from the position at which they are originated and employing thepicked up impulses to produce impulses of a greater and operative magnitude; accumulating these electrical impulses so as to build up an electro-potential charge; and

directing the electro-potential charge to an electro-responsive means for producing said desired action.

5. A method of producing a desired action in a well below the surface of the earth, comprising: transmitting along the wall structure of the well impulses of a frequency-below the impulse suppression value of the subsurface structure between the position at which the impulses are originated and the position at which they are picked up; picking up these impulses at a position remote from the position at which they are originated and employing the picked up impulses to produce impulses of greater and operative magnitude; accumulating these electrical impulses so as to build up an electro-potential charge; and directing the electro-po'tential charge to an electro-responsive means for producing said desired action.

6. A method for actuating in a wella perforating gun or other device having electro-responsive '7. A method for actuating in a well a perforat-' ing gun or other device having electro-responsive means for the operation thereof, comprising: transmitting down through the wall structure of the well impulses having a frequency below the impulse suppression value of the subsurfacestructure between the position at which the impulses are originated and the position at which they are picked up; picking up in the proximity of said device said impulses and stray impulses; separatingsaid transmitted impulses from said stray impulses; magnifying and accumulating said transmitted impulses; and directing the accumulation of said transmitted and magnified impulses through said electro-responsive means.

8. In means for actuating in a. cavity below the surface of the earth, a device having electro-responsive actuating means, the combination of: means for app g potential impulses to the earth; means in proximity to said device for picking up said potential impulses and under control thereof directing an actuating current to said electro-responsive means of said device, comprismeans for accumulating the magnified impulses which pass through said blocking means; means connecting said" storage means to said electroresponsive means of said device; and an electrical valve for controlling the discharge of said storage means through said electro-responsive control thereof directing an actuating current to said electro-responsive means of said device, comprising means to engage said wall of the cavity to receive impulses therefrom; means for employing said impulses to produce electro-potential impulses. of greater magnitude; means for blocking electro-potential impulses of a frequency different from said frequency; storage 1 means for accumulating the magnified impulses ing means to receive said impulses; means for employing said impulses to produce electro-potential impulses of greater magnitude; storage means for accumulating said impulses of greater magnitude; means connecting said storage means to said electro-responsive means of said device;

and an electricalyalve for controlling the disfrequency to the wall structure of said cavity;

means in proximity to said device for picking up said potential impulses and under control thereof directing an actuating current to said electroresponsive means of said device, comprising means to engage said wall structure of the cavity to receive impulses therefrom; means for employing said impulses to produce electro-potential impulses of greater magnitude; means for blocking electro-potential impulses of a frequency different from said selected frequency; storage} which pass through said blocking means; means connecting said storage means to said electroresponsive means of said device; and an elec trical valve for controlling the discharge of said storage means through said electro-responsive means. 11,. Means for actuating in a well perforating gun or other device having electro-responsive means for actuation thereof, the combination of means for applying electro -potential impulses to the upper part of the wallstructure of the well so that said impulses will travel down said wall structure; means engaging the wall structure of the well at spaced points and having parts operating in response to the potential drop between said spaced points to produce an actuating current; and means to direct said actuating current to said electro-responsive means of said gun.

12. Means for actuating in a well a perforating gun having electro-responsive means forac of said gun.

13. Means for actuating in a well a perforating gun having electro-responsive means for actuation thereof, the combination of means for, applying to the upper part of the wall of the well electro-potential impulses so that said impulses will travel down said wall; means connected to saidgun engaging the wall of the well at spaced points in proximity thereto and having parts opcrating in response .to the potential drop between said spaced points to produce current impulses; means for accumulating said current impulses; and meansfor feeding said accumulated current impulses to said electro-responsive means of said gun.

PHILIP W. MARTIN. 

